Asthma is an allergic disease of the airways that has reached epidemic proportions and represents a significant burden on health services globally. Asthma is characterized by a dysregulated adaptive immune response initiated by Th2 cells~ however, our understanding of why the disease develops is limited. Delineating the mechanisms which regulate the gene expression programs that define Th2 differentiation and effector function will be essential if we are to fully understand the etiology of asthma or develop new therapies. The recently identified family of large intergenic non coding RNAs (lincRNAs) has been shown to regulate core gene expression programs. Hundreds of lincRNAs are differentially expressed within cells of the immune system highlighting the exciting potential for an important role for lincRNAs in defining immune cell identity and function, as well as contributing to immunopathologies such as asthma. However, very little is known about the function of lincRNAs in vivo and their role in asthma is completely unknown. We hypothesize that Th2 cells express specific lincRNAs that are instrumental in regulating the gene expression programs that determine Th2 differentiation, Th2 effector function and susceptibility to asthma. Using state-of-the-art methodologies this proposal seeks to identify and characterize lincRNAs specifically expressed in Th2 cells and evaluate their biological function in vivo by using a murine model of allergic airway disease. Aim 1 will identify specific lincRNAs expressed in Th2 cells generated in vitro and in vivo and determine at which stage in the Th2 differentiation program they are expressed~ this will reveal lincRNAs most likely to be involved in directing Th2 differentiation. Aim 2 will use knockdown and overexpression studies to define lincRNAs with the ability to modulate Th2 cytokine production in vitro. In parallel, high-throughput RNA-sequencing combined with robust network and guilt-by-association computational analyses will be utilized to generate testable predictions for the function of each lincRNA. Aim 3 will use the recently developed Cas9 gene targeting technology to generate mice deficient in Th2 specific lincRNAs. By modeling allergic airway disease in these animals the potential role for lincRNAs in the etiology of asthma will be dissected in vivo for the first time. In summary this proposal will test the previously unexplored function of lincRNAs in asthma and represents a novel avenue in allergic airway disease research. These studies will not only identify previously unstudied lincRNAs but will aso provide critical information on their function in Th2 cells. Furthermore, as the majoriy of murine lincRNAs exist as syntenic orthologues in humans the work established in this proposal will ultimately serve as a platform for future analysis of human lincRNAs in asthma.